1. Field of the Invention
The present invention relates to a device and method of calculating a consumed amount of toner in image-forming apparatuses such as laser beam printers which print images by the use of laser beams, and more particularly, to a device and method of more precisely calculating a consumed amount of toner in image-forming apparatuses the use of a weight depending on a consumed amount of the toner, wherein the weight is obtained based on a task mode and an image data type.
2. Description of the Related Art
In general, image-forming apparatuses such as photocopiers, printers, combination office machines, and facsimile machines print the images stored in a recording medium on a print medium, and a developer such as toner is used to print the images on the print medium.
Therefore, in general, the image-forming apparatuses have a function providing users with information on a remaining amount of toner so that a toner cartridge can be timely replaced.
The conventional method to provide the information on a remaining amount of the toner detects and notifies users of the remaining amount of toner in a toner cartridge when necessary through a toner-detecting sensor. The toner detection sensor has a light emitter and a light receiver that are installed in the toner cartridge. However, the method additionally needs a detection circuit related to the toner-detecting sensor, which increases the manufacturing cost of the image-forming apparatuses.
Another method of providing the information on a remaining amount of the toner counts the number of copies of paper just after a new toner cartridge has been installed, decides that little or no toner is remaining in the cartridge if the number of copies is over a certain number, and notifies users that little or no toner is left. However, since the method is based on the calculation under the assumption that the toner necessary to print on one sheet of paper amounts to 4 to 5% of the whole area of the sheet on average, it may happen that an amount of toner can not be enough to print as many copies as guaranteed by a toner cartridge supplier. Alternatively, on the contrary, the toner cartridge has toner left therein even after the guaranteed number of copies has been printed, depending on image patterns such as a solid pattern of black spots, or a character pattern. These patterns may be lines and characters, a halftone pattern such as graphs and drawings, and so on, which are substantially printed on the copies.
In order to solve the above and/or other problems, a method has been developed and used that calculates a consumed amount of toner by counting the number of pixels of data to be printed (hereinafter, referred to as print data) in synchronization with a video clock and multiplying a coefficient of the consumed amount of toner per pixel based on a counted value.
However, the method calculates the consumed amount of toner using only the number of pixels of the data that has been counted, which causes a problem in that the method can miscalculate the consumed amount of toner. This is because the method fails to reflect the differences between the consumed amounts of toner depending upon task modes such as a print mode, photocopy mode, and so on, and image patterns such as a solid pattern, character pattern, halftone pattern, and so on. This is due to the fringe effect even when printed copies each have the same printed area or range thereon.
For example, Table 1 as below shows a result of the applicant's experiments in which the consumed amounts of toner per pixel differ from one another depending on the task modes and printed image patterns. As shown in Table 1, the toner is most consumed for the halftone pattern in the print mode, and the toner is most consumed for the solid pattern in the lower-level photocopy mode of the copy modes.
TABLE 15% Character5% Halftone5% Solid PatternPatternPatternPrint Mode1.37 × 10−08 g1.34 × 10−08 g1.43 × 10−08 gPhotocopy mode2.34 × 10−08 g1.92 × 10−08 g1.44 × 10−08 gIn order to solve the above and/or other problems, a method has been proposed, that uses a laser diode turn-on ratio. The ratio is calculated by counting a frequency of laser beams emitted from a laser diode by pixel as a correction coefficient when a consumed amount of toner is calculated by multiplying the counted number of pixels by a toner consumption amount coefficient.However, the method has a problem of generating software errors due to the overload to software processing data when reading a frequency of pixels of the data to be printed.
Further, the method reads the laser diode turn-on ratios with respect to the solid pattern and the halftone pattern as values similar to each other when documents are scanned in the lower-level photocopy mode of the photocopy modes. Thus, the consumed amounts of toner for the solid pattern and the halftone pattern are calculated to have values similar to each other. Therefore, the method has a problem that the difference of the consumed amounts of toner between the solid pattern and the halftone pattern is not precisely reflected.